Refactor battery and charging for robustness and to support future products

Librem 14 behavior is preserved except for some specifically targeted fixes.

Behavior changes for Librem 14:

1. Unplugging and re-plugging AC adapter within 1 second now re-enables charging correctly
   • Previously, charging stopped unexpectedly since BQ24715 automatically sets charge current to 0 on AC unplug
2. Plugging in AC just as system shuts down works correctly
   • Previously, the EC would lower SMC_SHUTDOWN_N but then would continue running as-is if the system didn't actually shut off
   • Booting again, then unplugging AC would cause the system to shut off unexpectedly
   • The EC now detects that the system didn't shut off and raises SMC_SHUTDOWN_N again
3. Keyboard latency and dropped keys due to 1-second event are improved
   • Trimmed and optimized periodic battery tracing to reduce time spent in 1-second event
   • Staggered battery/charger events to reduce maximum latency
4. At PoR, just program bq24715 registers, don't enable charge and then immediately disable it
   • battery_charger_init() does that (if bq24715 is powered)
5. Debug commands are now provided (via ectool) to test behaviors that are otherwise untestable
   • Debug commands are never damaging but can produce behaviors that otherwise "never occur", like charger validation errors or EC freezes

bq24715 charger implementation was refactored:

• Support chargers only powered by AC (board option)
• Support enabling IDPM (board option)
• Reduce coupling to SBS battery and Librem 14 board logic
• Improve robustness
  • Validate programmed parameters periodically, disable charger and reprogram if any problem is detected (battery logic can try to re-enable charger)
  • Validate input values like charge current / voltage for bq24715 valid range
  • Improve output for unexpected conditions like parameters out of range
  • Provide debug commands to test validation

sbs_battery (SBS battery host implementation) was extracted from Librem 14 board_battery.c

scripts/ectool.sh

@@ -3,4 +3,6 @@
 
 set -e
 cargo build --release --manifest-path tool/Cargo.toml
-sudo tool/target/release/system76_ectool "$@"
+if [ "$#" -gt 0 ]; then
+    sudo tool/target/release/purism_ectool "$@"
+fi